"Health reasons have forced blues musician Gregg Allman to cancel his Sunday performance at the Safeway Waterfront Blues Festival presented by First Tech Federal Credit Union. Fortunately for attendees, Curtis Salgado has rearranged his tour schedule and is flying back to close out the festival," event organizers said in a statement.

“There is no way we could have foreseen this change to our lineup,” Laura Golino de Lovato, the Oregon Food Bank's director of development, marketing and communications said in the statement. “We are so thankful that Curtis was willing and able to step in. He loves this community and the fans love him.”

It's true. We're sad to confirm Gregg Allman has cancelled his performance on Sunday due to health reasons. We wish him a speedy recovery...

"Due to unforeseen circumstances, Gregg Allman has been forced to cancel this week’s upcoming shows," his agency said in a statement to the Oregonian. "He apologizes for inconveniencing his fans and hopes to return to these cities as soon as possible. The dates that are being effected by these cancellations are July 2 in Woodland Park, WA and July 6 in Portland, OR."

Salgado is a Blues Festival veteran, having appeared in its first year -- when it was the Rose City Blues Festival -- in 1987. In recent years, the musician has beaten liver and lung cancer and returned with the award-winning album "Soul Shot."

Festival organizers will be answering questions at a press conference this afternoon. More info to come as this story develops.